1. Presented by Hermes YH Liu
Relay-Based Deployment Concepts for Wireless and Mobile Broadband Radio from IEEE Communication Magazine Sep. 2004
Presented by Hermes YH Liu
2018/11/15
OPLAB, Dep. of Information Management, NTU

2. OPLAB, Dep. of Information Management, NTU
Authors
Ralf Pabst, Bernhard H. Walke, and Daniel C. Schultz, RWTH Aachen University
Patrick Herhold, Gerhard P. Fettweis Technical University of Dresden
Halim Yanikomeroglu, David D. Falconer Carleton University
Sayandev Mukherjee and Harish Viswanathan, Lucent Technologies
Matthias Lott and Wolfgang Zirwas, SIEMENS ICM
Mischa Dohler and Hamid Aghvami, Kings College
2018/11/15
OPLAB, Dep. of Information Management, NTU

3. OPLAB, Dep. of Information Management, NTU
Agenda
Introduction
The State of the Art
Multihop Operation
Cooperative Relaying and Virtual Antenna Arrays
Routing and Radio resource Management
WMS: A Prototypical Cellular Relay Network
Conclusions
2018/11/15
OPLAB, Dep. of Information Management, NTU

4. OPLAB, Dep. of Information Management, NTU
Agenda
Introduction
The State of the Art
Multihop Operation
Cooperative Relaying and Virtual Antenna Arrays
Routing and Radio resource Management
WMS: A Prototypical Cellular Relay Network
Conclusions
2018/11/15
OPLAB, Dep. of Information Management, NTU

5. OPLAB, Dep. of Information Management, NTU
Introduction
Multihop-augmented infrastructure-based networks:
1. seed concept in 3GPP(3rd generation Partnership Project)
2. mesh networks in IEEE
3. coverage extension of HiperLAN/2 through relays or user-cooperative
diversity mesh networks
Benefits via relays:
1. radio range extension (mobile and wireless broadband cellular network)
2. combat shadowing at high radio frequencies
3. reduce infrastructure deployment costs
4. enhance capacity in cellular networks
2018/11/15
OPLAB, Dep. of Information Management, NTU

6. OPLAB, Dep. of Information Management, NTU
Introduction
4G cellular systems do not feasible with the current cellular architecture due to:
1. the transmission rates of 4G are two orders of magnitude higher than
3G, this creates power concerns:
–for a given transmit power level, the symbol/bit energy ( , energy
per symbol/ bit) decreases linearly with the increasing transmission
rate
2. The spectrum for 4G will be located 2GHz above 3G, the radio
propagation is significantly more vulnerable to non-line-of-sight (non-
LOS), which is typical mode of today’s urban cellular system
2018/11/15
OPLAB, Dep. of Information Management, NTU

7. OPLAB, Dep. of Information Management, NTU
Introduction
Drawbacks of increase the density of base stations (BS):
1. deployment cost
2. transmission cost (data/bit vs. voice/bit)
2018/11/15
OPLAB, Dep. of Information Management, NTU

8. OPLAB, Dep. of Information Management, NTU
Introduction
Virtue of multihop wireless network:
1. transmit power is significantly reduced
– conventional cellular networks have cells of diameter 2-5 km,
while relay has m in diameter
– relay does not need to be as high as BS, reducing tower leasing and
maintenance costs
2. relays are wireless
3. solving coverage problem for high data rates in larger cells
4. capacity gains can be achieved with reuse efficiency or spatial diversity
2018/11/15
OPLAB, Dep. of Information Management, NTU

9. OPLAB, Dep. of Information Management, NTU
Introduction
Virtue of multihop wireless network:
5. the relay-to-user links could use different (unlicensed) spectrum (e.g.,
IEEE x) than the BS-to-user links (licensed spectrum)
6. Do not need complicated distributed routing algorithms as ad hoc
networks
— ad hoc: function without any infrastructure
— relay: very-high-data-rate coverage and throughput
2018/11/15
OPLAB, Dep. of Information Management, NTU

10. OPLAB, Dep. of Information Management, NTU
Agenda
Introduction
The State of the Art
Multihop Operation
Cooperative Relaying and Virtual Antenna Arrays
Routing and Radio resource Management
WMS: A Prototypical Cellular Relay Network
Conclusions
2018/11/15
OPLAB, Dep. of Information Management, NTU

11. OPLAB, Dep. of Information Management, NTU
The State of the Art
Bidirectional amplifiers have been used in 2G and 3G systems
—analog repeaters, increase noise and suffer instability
ETSI/DECT standard in 1998 was the first specifying fixed relays (called
wireless BSs) for cordless systems using TDM channels for voice and data communications
TDMA, F/TDMA, CDMA, FDD (uplink and downlink)…., and can easily be
extended to packet-based systems
ETSI- broadband radio access network (BRAN), high-performance LAN (HiperLAN/1,2), IEEE x have elements to operate ad hoc networks
Europe telecommunication standard institute/Digital enhanced cordless telephony
但是目前沒有實際應用relay的具體應用
2018/11/15
OPLAB, Dep. of Information Management, NTU

12. OPLAB, Dep. of Information Management, NTU
The State of the Art
Relaying systems:
— decode-and forward: digital repeaters, bridges, or routers. Regenerate
the signal by fully decoding and reencoding the signals prior to
retransmission
— amplify-and forward: analog repeater, increase the noise level
2018/11/15
OPLAB, Dep. of Information Management, NTU

13. OPLAB, Dep. of Information Management, NTU
Agenda
Introduction
The State of the Art
Multihop Operation
Cooperative Relaying and Virtual Antenna Arrays
Routing and Radio resource Management
WMS: A Prototypical Cellular Relay Network
Conclusions
2018/11/15
OPLAB, Dep. of Information Management, NTU

14. OPLAB, Dep. of Information Management, NTU
Multihop Operation
The intersection can be covered well by the
AP.
Nearby streets can only be served if line-of-sight
(LOS) connectivity is available between a mobile
terminal and its serving station, due to the
difficult radio propagation condition, ex. In the
5-6 GHz frequency band
Figure 1. a Manhattan scenario with one AP (serving
the white area) and four RSs covering the shadowed
areas around the corners shown in beige.
2018/11/15
OPLAB, Dep. of Information Management, NTU

15. OPLAB, Dep. of Information Management, NTU
Multihop Operation
RS have to route the traffic to AP for two ways:
1. Via intermediate RS using a low-rate but robust
combination modulation and coding (PHY mode)
2. Via RSs and using a faster PHY mode and
thus higher link capacity
Figure 2. a schematic of Manhattan scenario
2018/11/15
OPLAB, Dep. of Information Management, NTU

16. OPLAB, Dep. of Information Management, NTU
Multihop Operation
The basic element of Fig. 1 can be repeated to cover
a wide area
Figure 3. wide-area coverage using the basic element
2018/11/15
OPLAB, Dep. of Information Management, NTU

17. OPLAB, Dep. of Information Management, NTU
Multihop Operation
a) AP and RSs operating at the same
carrier frequency while accessing
the physical medium in time multiplex
b) AP and RSs operating at different
carrier frequencies
c) A fixed RS operate to bridge the
distance between AP and the second
RS where direct communication
between the AP and the second RS
is not possible due to lack of LOS
Figure 4. Examples of relay concepts
2018/11/15
OPLAB, Dep. of Information Management, NTU

18. OPLAB, Dep. of Information Management, NTU
Multihop Operation
Figure 5. Analytical estimation of the extension of the radio range of an AP by relays with receive antenna gain
2018/11/15
OPLAB, Dep. of Information Management, NTU

19. OPLAB, Dep. of Information Management, NTU
Multihop Operation
Relaying function in OSI reference model:
Physical: repeater
link: bridge
network: router
2018/11/15
OPLAB, Dep. of Information Management, NTU

20. OPLAB, Dep. of Information Management, NTU
Multihop Operation
Figure 6. Left: a fixed wireless router at an intersection to extend the radio range of an AP around the corner into a
shadowed area to serve a remote mobile terminal. Right: maximum end-to-end throughput vs. distance for
forwarding under LOS conditions with directed receive antennas having a gain of 11 dB
2018/11/15
OPLAB, Dep. of Information Management, NTU

21. OPLAB, Dep. of Information Management, NTU
Multihop Operation
Benefits of relaying summary:
— throughput
— coverage
— radio resource reuse (ex. frequency reuse)
— cost advantage
2018/11/15
OPLAB, Dep. of Information Management, NTU

22. OPLAB, Dep. of Information Management, NTU
Agenda
Introduction
The State of the Art
Multihop Operation
Cooperative Relaying and Virtual Antenna Arrays
Routing and Radio resource Management
WMS: A Prototypical Cellular Relay Network
Conclusions
2018/11/15
OPLAB, Dep. of Information Management, NTU

23. Cooperative Relaying and Virtual Antenna Arrays
Conventional relay:
store-and-forward in a relay chain. A receiver solely copy the data sent by
its respective transmitter, while discards emissions from other transmitters
Cooperative relay:
1. broadcast nature
2. achieve diversity through independent channels
A signal, once transmitted, can be received (and usually forward) by multiple terminals
Multipass interference 會造成fading, 不過cooperative反而利用這些interference 來增加transmit gain
2018/11/15
OPLAB, Dep. of Information Management, NTU

24. Cooperative Relaying and Virtual Antenna Arrays
each relay becomes part of a larger
distributed array
Challenge:
synchronization, availability of channel state
information, and appropriate cluster formation
Figure 8. The concept of cooperative relay (a)
2018/11/15
OPLAB, Dep. of Information Management, NTU

25. Cooperative Relaying and Virtual Antenna Arrays
Benefits of cooperative relay:
1. path loss saving
2. power gain
— each of the relays add additional transmit power combined in the
destination terminal
3. macrodiversity gain allows combating shadowing
The integration of multiple-input-multiple-output (MIMO) and so-called dirty paper coding techniques may lead to advanced multihop networks with high spectral efficiency
2018/11/15
OPLAB, Dep. of Information Management, NTU

26. Cooperative Relaying and Virtual Antenna Arrays
Type of cooperative protocols:
1. static:
the relay nodes constantly retransmit data of their received signals
2. adaptive:
allowing feedback and/or signaling between forwarding nodes, the relays
resend signals only when they believe it to be helpful for the destination
node. The adaptation may be done independently or jointly for all relays
if information is exchanged between the relays
2018/11/15
OPLAB, Dep. of Information Management, NTU

27. Cooperative Relaying and Virtual Antenna Arrays
Group together closely spaced relays to form
a stage.
The source node transmits to the relays
in the first stage, which then use space-time
coding in a distributed manner to retransmit
the signal to the next stage
Figure 9. The concept of cooperative relay (b)
Figure 10. Space-time coding
2018/11/15
OPLAB, Dep. of Information Management, NTU

28. OPLAB, Dep. of Information Management, NTU
Agenda
Introduction
The State of the Art
Multihop Operation
Cooperative Relaying and Virtual Antenna Arrays
Routing and Radio resource Management
WMS: A Prototypical Cellular Relay Network
Conclusions
2018/11/15
OPLAB, Dep. of Information Management, NTU

29. Routing and Radio resource Management
Routing algorithms for mobile ad hoc network (MANET) have high routing overhead and low efficiency in network throughput
It is proposed that routing in the multihop network be supported by an area-wide cellular overlay network, where route requests are sent to the BS of the overlaying cellular networks which called Cellular Based Multihop (CBM) routing
Determines the route and responds with a packet comprising a series of mobile nodes willing to relay the data traffic between the source and destinations
Both macro network to communicate with all nodes and throughput efficiency of multihop transmission in the microrange layer
2018/11/15
OPLAB, Dep. of Information Management, NTU

30. Routing and Radio resource Management
Figure 11. Hierarchical system architecture for a Service Specialized System (SSS)
2018/11/15
OPLAB, Dep. of Information Management, NTU

31. Routing and Radio resource Management
Figure 12. comparison delivery rate and delay of CBM (Cellular Based Multihop) and DSR (Dynamic Source Routing)
CBM delivers more packets and has minimum delay– leads to less packet drops due
to wrong route information
2018/11/15
OPLAB, Dep. of Information Management, NTU

32. Routing and Radio resource Management
1. performance gains due to no. relays increase when terminals increase
2. the maximum relay transmit power is important only in large cells
3. performance gains are quite sensitive to the relay selection criterion
— wrong relay is worse than no relay
4. once a good relay is selected, performance gains becomes fairly
insensitive to the relay channel selection criterion
5. selection criteria involve the mutual interference between relay channels
2018/11/15
OPLAB, Dep. of Information Management, NTU

33. OPLAB, Dep. of Information Management, NTU
Agenda
Introduction
The State of the Art
Multihop Operation
Cooperative Relaying and Virtual Antenna Arrays
Routing and Radio resource Management
WMS: A Prototypical Cellular Relay Network
Conclusions
2018/11/15
OPLAB, Dep. of Information Management, NTU

34. OPLAB, Dep. of Information Management, NTU
Figure 13. Wireless media system: integration with mobile radio
2018/11/15
OPLAB, Dep. of Information Management, NTU

35. WMS: A Prototypical Cellular Relay Network
Wireless Media System (WMS):
1. intended to have very high multiplexing data rate between Mb/s, the
spectrum bands (ex. Beyond 3GHz, or even 5GHz) will allow very small
equipment size for picocellular BSs/APs and RSs, including the antennas
2. WMS is integrated into a 3G system sharing
— An IPv6 based fixed core network
— Functions of the cellular system like subscriber identity module (SIM),
Authentication, authorization, and accounting (AAA), and localization
3. both APs and RSs appear like a BS to a mobile terminal
4. cost efficient and flexible infrastructure
2018/11/15
OPLAB, Dep. of Information Management, NTU

36. OPLAB, Dep. of Information Management, NTU
Agenda
Introduction
The State of the Art
Multihop Operation
Cooperative Relaying and Virtual Antenna Arrays
Routing and Radio resource Management
WMS: A Prototypical Cellular Relay Network
Conclusions
2018/11/15
OPLAB, Dep. of Information Management, NTU

37. OPLAB, Dep. of Information Management, NTU
Conclusions
Cooperative use of relays forming virtual antenna arrays to exploit the spatial diversity leading to increases in available capacity
WMS, a concept for a mobile broadband system based on fixed relay stations
Multihop communications can provide a substantial increase in network capacity when suffering from heavy path loss
The very high capacity can be traded for radio range which would otherwise be limited due to high attenuation at high radio frequencies
2018/11/15
OPLAB, Dep. of Information Management, NTU

38. OPLAB, Dep. of Information Management, NTU
Conclusions
Future works:
1. virtual arrays
2. multiple access and multiplexing schemes
3. combination of medium access and radio resource management
protocols for multihop networks
4. relay system in IEEE j Relay
2018/11/15
OPLAB, Dep. of Information Management, NTU

39. OPLAB, Dep. of Information Management, NTU
The End
Thanks for Listening!!
2018/11/15
OPLAB, Dep. of Information Management, NTU

40. OPLAB, Dep. of Information Management, NTU
3G vs. 4G
Frequency
Transmission Rate 3G
1.8~ 2.5 GHz
2Mbps (384kbps general) 4G
2~ 8 GHz
High speed (250km/h): 2Mbps
Mid speed (60km/h): 20Mbps
Low speed (in house): 100Mbps
2018/11/15
OPLAB, Dep. of Information Management, NTU

41. OPLAB, Dep. of Information Management, NTU
Definitions
Reuse efficiency: a radio channel which is occupied in one microzone can be used in adjacent microzones
Spatial diversity: one of the antenna diversity techniques, uses multiple antennas, antennas arrays to transmit/receive signals
2018/11/15
OPLAB, Dep. of Information Management, NTU

42. OPLAB, Dep. of Information Management, NTU
Definitions
Gain: An antenna characteristic that increases the power density in a
given direction by concentration of radiated energy
Gain is given in reference to a standard antenna. An antenna gain of 2 (3
dB) compared to an isotropic antenna would be written as 3 dBi. An
antenna gain of 1 (0 dB) compared to a dipole antenna would be written
as 0 dBd
Use the following conversion factor to convert between dBd and dBi: 0
dBd = 2.15 dBi
2018/11/15
OPLAB, Dep. of Information Management, NTU

43. OPLAB, Dep. of Information Management, NTU
Definitions
MIMO: MIMO algorithms in a radio chipset send information out over two or more
antennas. The radio signals reflect off objects, creating multiple paths that
in conventional radios cause interference and fading. But MIMO uses these
paths to carry more information, which is recombined on the receiving side
by the MIMO algorithms (
MIMO can also be used in conjunction with OFDM, and is part of the IEEE
standard and will also be part of the IEEE n High-Throughput standard,
which is expected to be finalized in mid Standardization of MIMO to be used
in 3G standards such as HSDPA is currently under way.
Spectral efficiency: bit/sec/Hz
2018/11/15
OPLAB, Dep. of Information Management, NTU

44. OPLAB, Dep. of Information Management, NTU
Definitions
Dirty paper coding: dirty-paper coding
means techniques that allow a transmitter
to send information so that each use sees
no interference from other users
From IEEE SIGNAL PROCESSING MAGAZINE
2018/11/15
OPLAB, Dep. of Information Management, NTU